Hoist brake and control system



Panarea Jamais, lose UNK@ HOXST BRAKE AND CONTROL SYSTEM Barry F. Vickers, Detroit, Mich., assigner to p Vickers, Incorporated, Detroit, Mich., a corpol ration of Michigan Application December A15, 1939, Serial No. 309,459 (ci. 19e- 144) malins.

This invention relates to a hoisting control system.

In hoisting systems in which the motive power is liquid under pressure, two problems arise. One is to keep the pressure lines between the source and motor :llllcdl with liquid; another is to provide aneiective means for releasing the brake on the hoist.

An object of the present invention is to provide brake release means which requires a relatively small source of auxiliary pressure for operation.

A further object is to provide a means associated with the auxiliary pressure system for maintaining the proper volume or' power liquid functioning between-the source and the hoisting motor. Another object of the invention has to do with the provision of a novel control means whereby the travel of the hoist can be accurately controlled.

Other objects and features of the invention, having to do with details of construction and operation, will be brought out in scription and claims.

In the drawing:

Fig, 1 is a circuit diagram showing the esseny tial elements of the invention.

the following de- Fig. 2 is a detailed view of the brake mechanism used for the holst.

Referring to the drawing, a hoist drive wheel is shown at IU arranged to be driven through gears Il and I2 rotated by a reversible hydraulic motor I3. A reversible variable delivery pump I4 supplies iluid under pressure to the motor` I 3 through lines i5 and I8 used alternately as pressure or exhaust lines.:v An electric motor I1 or other source of power drives the pump Il and also a pilot pump I8.

The reversible pump vIl has a movable member 20 which may be shifted in one direction or another to determine the direction of flow through the pump Il and the direction of the motor I3. A hand lever 2i is connected to the member 2li through linkage 22, 23,' which is connected by a spring 24. Movement of the hand lever 2lv to the hoist position indicated, will shift pump Il offcenter upwardly to cause dow of liquid under pressure to line I 5. Ignoring for the moment the braking mechanism, it will be seen that a threaded shaft 25 is connected at one end to a bracket 26. A gear nut 21 runs oil from the gear II and, consequently, shifting of the hoist wheel I will cause a shifting of the shaft 25. 'Ihe is a hoist cam 29 and a lowering cam 30. A lever 3l is pivoted at 32 on a stationary upright 33.

Each end of the lever 3i is provided with a downward projection which is adapted to cooperate alternatelywith the two cams 29 and 3D. The

right end of lever 3l is pivoted at 3d to link 28 so that the movement of the cams may control the movement of the member 20 on the pump. Consequently, at the end of each movement of the hoist, there will be a proper deceleration and stopping.

An outputV pipe :ld from pump I8 leads to acylnder #Si and also to a valve block l2 through branches 113 and d, respectively. Cylinder 4I has a free piston d located therein backed by a spring 6. Spaced from the inlet end of the cylinder il is an outlet pipe dl. This cylinder will serve as a reservoir for the output of the pump and also as a bypassoutlet when the liquid stored in the cylinder di is subjected to such a pressure that4 thefree piston :l5 will be moved down against spring @i8 to allow bypassing through pipe al. Branch M leeds directly through the housing l2 to a directional valve d8. This valve consists of a shaft which has spaced spools' 139, t, di, 52 and 53. As the valve is viewed in the drawing, the spool l is blocking conduit lill and also a branch conduit 5d from a conduit leading from thehouslng 'd2 to a brake cylinder 56. The valve 4l is connected by-,a rod 5l to a'lever 58 which is also responsive to the movement of link 23 and handlever 2|. Consequently, when valve 48 is shifted in either direction, pressure from pilot pump I 8 and also Vfrom cylinder 4I will beavailable to the brake cylinder 56. This cylinder is shown in section in Fig. 2. A piston 59 within the cylinder is oo nnected to a rod and a spring Si urges the` inder 56 tends to maintain the brakes in locked or engaged position through the cam 63. A tension spring 61 serves to release the brake shoes when pressure is introduced into the cylinder 58 through conduit 55. Consequently. it will be bracket 2S is directed to a cam table 28 on which seen that when the controllever 2Iis shifted in either direction pressure frompilot pump Il and the reserve cylinder 4I will be instantly available to release the brake on the hoist. 'Ihis tends to cut down the drag on the hoist which would otherwise result if the pilot pump itself were required to build up the pressure to shift Y -'Il when the valve up for any leakage may be exerted by driving said motor,

. source and s'aid cylinder,

`said mechanism supplying liquid under pressure the brake piston. The outlet iiuid of pilot pump II has thesame pressure asfiuidinthe cylinder 4i. The cylinder Il, through spring actuated piston si, furnishes extra volume for releasing the brake quickly. Spring Il determines the pressure.

A conduit Il located in housing Il, is connected to the atmosphere at one end and also to conduit Il is in the position shown. However. upon shifting of valve 4l downward. the spool Il will close the atmospheric outlet oi' conduit Il and if the valve is shifted upwardly, the spool Il will perform the same function. The valve It and the housing 42 are connected to conduits il and il by conduits 1I and 1I. respectively. It will be seen that the line 44 from pilot valve Il is open to line 1i through a check valve 12 and to line 1l through a rcheck valve 13.A These check valves are set at a certain preissure so that pilot pump may supply oil -to make in the closed circuit bythe pump. Il 'and motor Il. Bypassing relief valves 1e and 1l are provided to limit the pressure which' the pump on the motor Il.

l. A braking apparatus for a hydraulically op erated mechanism, including a motor for driving said meachanism and a driven member, lmeans for a brake for holding said mechanism against movement, means for holding said brake'in engaged position, means for releasing said brake comprising a piston and cylinder, a source of pressure, a conduit connecting 4*said a valve in said conduit for controlling the supply of liquid under pressure to said piston and cylinder, a supplementary source of pressure comprising a cylinder. a movable member within said cylinder for resistinl the entrance of liquid therein, means connecting said conduit with said supplementary supply means, and means responsive to the movement of said valve and the admission of liquid under pressure to said brake releaslnl means.

2. In a brake system for a hydraulic mecha nism including, a member to b e shifted, a hydraulic motor for shifting said member nected thereto, a variable displacement motor. means `for controlling operably confor controlling the position of inl means,

e and a brake means for said m v displacement thereof and attlleendofa assnoss rate of movement of said motor, a brake for said shifted arranged tnbe hydraulically responsive to moverate and directional ing said l r, a pressure forming means, con duit means for forming'a said motor and said pressure forming means, an independent source of pilot pressure. and means connecting said closed system and said pilot pressure including a valve whereby a supply line to the pressure forming means in said closed system may be connected to said pilot pressure to rcplenish liquid in said closed system.

4. In a brake system for a hydraulic mechanism. s member to be shifted a hydraulic motor for shifting said member. forming means. conduit means for forming a closed circuit between said motor and said pressure forman independent source of pilot pressure, and means connecting said closed system and said pilot pressure including a valve whereby a supply line to the press l forming means in said closed system may be connected to said pilot pressure to replenish liquid in; said closed system.

be operated by said valve whereby said member is braked at predetermlnedpoints in the movement of said mechanism.

5. In a brake apparatus for a hydraulic system including a member to b e shifted. a hydraulic motor device for shifting nected thereto, a pump device for supplying liquid under pressure to opera said motor device, shiftable means on one of d devices to control the shiftable yto control speed, deceleration and direction of the motor device. a brake for said member to be shifted arranged to be hydraulically operated, brake operating control means, and means cooperatively connecting said shiftable means and said brake operating control means to eifect brake operation deceleration movement of said HARRY P. VICKERS.

shif table means.

said member operably con- 

